common iliac vein, one of the two veins that are the sources of the inferior vena cava, formed by the union of the internal and external iliac veins, ventral to the sacroiliac articulation. Each common iliac vein receives the iliolumbar and, in some individuals, the lateral sacral veins. The left common iliac vein also receives the middle sacral vein. Neither of the common iliacs contains valves. Compare external iliac vein, internal iliac vein.
